Process of treating natural phosphates.



STATES PATENT Erica.

THIRDS TO A. H. AGNEW GINIA.

AND PARK AGNEW, OF ALEXANDRIA, VIR- PROCESS OF TREATING NATURALPHOSPHATES.

SPECIFICATION formingpart of Letters Patent N 0. 690,048, dated December31, 1901. Application filed February 16, 1901. Serial No. 47.636. pimens) T0 at whom, it may concern:

Be it known that I, Lnwrs CHEESEMAN, Sr., a citizen of the UnitedStates, residing at Alexandria, in the county of Alexandria and State ofVirginia, have invented a certain new and useful Process or Method ofTreating Phosphates, of which the following is a specification.

The object of my invention is the provision of an improved process ormethod of treating naturally-occurring phosphates, such as apatites,coprolites, rock, &c., whereby the insoluble companies thereof, astriphosphate of lime, may be converted into forms soluble in water orammonium citrate, thus making the phosphoric acid available, as socalled.

My invention consists, broadly, in passing a current of electricitythrough aliquid mixture of comminu ted natu rally-occurring phosphateand a suitable reagent and changing the insoluble phosphate of lime toforms soluble in ammonium citrate and water.

Further, it consists in passing a current of electricity through aliquid mixture of comminuted naturally-occurring phosphate and an acidsalt, such as acid sulfate of soda, (miter-cake.)

Further, it consists in passing a current of electricity through aliquid mixture of comminuted naturally-occurring phosphate and an acidsalt, such as miter-cake, and then evaporating the liquid or Water.

The successive steps of the process or method of treatment are asfollows:

First. The naturally-occurring phosphate is reduced to a fine powder orcomminuted in any well-known way, the treatmentto which it is subjecteddepending upon its form. It may be passed through a crusher, thenreduced to fine particles, and, if desired, screened to remove thecoarser particles.

Second. The fine particles or flour should be mixed in a suitablereceptacle with a liquid, preferably water and acid sulfate of soda,(niter-cake,) the relative quantities of each depending on the qualityof the phosphate and the substances with which it may be associated inits naturally-occurring state.

Third. A current of electricity is passed hard and soft phosphate;

through the mixture for a suitable period of time.

Fourth. The liquid or water is evaporated from the mixture.

During the third step of the process-tho mixture may behea ted andagitated, if desired. I find that the action of the electric currentupon the liquid mixture results in the formation of mono and dibasicphosphates, the monobasic being soluble in waterand the dibasic solublein ammonium citrate.

The chemical reactions aided by the electric current are as follows:

The reactions occur as specified Without the passage of the current, butless completely and require a longer time.

The vessel for receiving the liquid mixture should be of such materialthat it will not be acted upon by the acid solution.

The anode and cathode may be of platinum or any other substance orcomposition which may be found desirable.

At the close of the process there remains a residuum of monobasicphosphate, dibasic phosphate, and other compounds, the character ofwhich depends upon the nature of the elements present and associatedwith the naturally-occurring phosphate of lime which has been subjectedto treatment. This residuum contains so-called available phosphoricacid, and alone or when mixed with other substances is adapted to beused as a fertilizer.

In some instances propose to modify the process, especially when Idesire to obtain Watensoluble or monobasic phosphate. To this end Isiphon off or otherwise remove the liquid solution from the receptaclein which the mixture has been electrically treated and evaporate thewater. \Vhen this is effected by heat, I add to the solution sufficientsulfuric acid or nitric acid to render the same slightly acid. In thisway the salts soluble in Water remain water-soluble.

While I have specified acid sulfate of soda (niter-cake) as the reagentI propose to use in practice, I may substitute another or others withoutessentially changing the character of the process. a

What I claim is-- 1. The process of treating naturally-occurringphosphates, consisting in mixing the same in a finely-divided state withwater and an acid salt which by metathesis will change tribasicphosphate to mono or di basic phosphate or both, passing through themixture for a suitable period of time a current of electricity, andevaporating the water from the mixture.

2. The process of treating naturally-occurring phosphates, consisting inmixing the same with water and acid sulfate of soda (ni- 15 ter-cake),passing through the mixture and for a suitable period of time a currentof electricity, and evaporating the water from the mixture.

In testimony whereof I affix my signature :0 in presence of twowitnessses.

LEWIS CHEESEMAN, SR.

Witnesses: I

A. H. AGNEW, H. R. BURKE.

